Gluing fixture



Dec. 25, 1945.

c. F. KRAMER ET AL 2,391,426

' GLUING FIXTURE Filed Jan. 8, 1943 3 Sheets-Sheet l WGQNeIsm m? Krm r Dec. 25,1945. c. F. KRAMER ET AL GLUING FIXTURE Filed Jan. 8, 1943 5 Sheets-Sheet 2 v w GNeIsqnr e m K E C INVENTOR.

Patented Dec. 25, 1945 GLUING FIXTURE ClarenceFIKramer, Birmingham, and Walter G Nelson, Iron Mountain, Mich., assignors to Ford Motor Company, Dearbor'n,

.tion of Delaware Mich., a corpora- Y Application January s, 1943, sets-1N... 471,715 1 Claims. (01444-281) This invention is concerned with the assembly of structures withadhesive materials; and, more particularly, with an apparatus and method of operation thereof for'the construction of aircraft components using various adhesive features.

' Adhesives in various forms have long been used in the constructionof aircraft, and particularly so when such construction comprised wood and fabric components. In larger structures this has been generally superseded by all-metal construction and the use of rivets or welding; but in smaller craft and in those in which it is possible to use wood and fabricconstruction and thus avoid the use of critical metals, the earlier method is still followed. Indeed, an extension of the method may be expected to cover structures em pioying metal components, asadvances in re search develop adhesives which are efiicient in obtaining metal-to-metal joints. It will thus be seen that the adhesive process offersconsiderable promise as a means of'avoiding the repetitive work now required in'riveting and weld ing, with the consequent increase in speed of construction and saving of materials and time.

The'adhesive method has always required the use-of pressure and sometimes of heat (depending upon'the type of adhesive used) to perfect the bond between the components being joined; and many methods have been worked out to obtain these necessary conditions in connection with the various types of work to be performed. It is at thisparticular phase of the problem that the present invention is directed and the apparatus and method shown attack the problem in a novel way, resulting in joints of uniformly higher tions which will appear more fully from the drawings and the specification.

With these'and other objects in view,'the in-- vention consists in the arrangement, construction and combination of the various parts of the improved device described in the specification, claimed in theclaims, and illustrated in the accompariying drawings in which:

Figure 1 is a perspective view of a portion of one form of a gluing fixture. v

"Figure 2 is aperspective view of a second form of the apparatus on a somewhat larger scale.

Figure 3 is a section taken on the line 3-3 of Figure 2.

Figure 4 is an elevationof the device shown in Figure l.

Figures 1 and 4 show a portion of the fixture used for'securing plywood skin to ribs and formers to construct the leading edge component of an airframewing. Figure 2 shows another fixture forth'e simultaneousconstruction of' the leading edge and wing section which may be used where circumstances do not require the separableconstruction shown in Figure 1. The

strength obtainable with a minimum of time and labor.

An advantage of the method of apparatus shown is that a precise control of temperature and pressure is possible and this'control is such that itmaybe varied for specific parts of the structure which, by the nature of their construction, require special treatment. Another advantage is that the apparatus insures proper align-3 ment and forming of the structure so that'the successive structures made in the device are interchangeable and uniform throughout. Yet'an other advantage of the invention is that a minimum of heat is required and still the adhesive operation is concluded in a very short time. Other advantages number the saving in setup time of the various components, maintenance of these components in rigidly preselected posidons-provision made for ready removal of the completed structures, as well as other consideraoperation of each fixture is, however, similar, and in the interest of clarity, the work is shownin detail only in Figure 2. Referring'to the latter, the work in position is a portion of the leading edge structure 9 including the skin In which is preformed to substantially the shape shown, a rib H, which is prefabricated of a number of individual parts, and abulkhead I2. Omitted from the view 'are the usual formers which normally are positioned in the notches I3 in the longitudinal stiffening members [4 attached to the innor surface of the preformed skin Hi. It will be understood that the complete edge component comprises a number of additional units similar to those shown continuously arranged, but the view chosen is representative of the whole. The distinction between Figures 1 and 2 is that in the former, the edge component alone is constructed, mbly of both edge and win'g'is contemplated.

The assembly of the edge component, as shown in Figures 1 and 4, takes place on an extended worktable l5 whichcorresponds to one of the spars of the completed wing structure. Associated with this intermediate length is the press l6-which includes a supporting frame IT to which are hingeda number of movable skin pressure strips l8 and fixed strip 42 arranged in spacing to conform to the rib, former and bulkhead spacing of the structure desired and'having inner faces I!) conforming to the exterior curvature of the structure which is shown in dotted line at 3|. Strips 18 are hinged on the link 44 to frame I! at bracket 20 so they may be Withdrawn laterally and upwardly as indicated by the dotted line position to clear the work table to permit ready assembly of the structural component and its removal after the adhesive operation has been completedjas well, .to 'insure that iitwill occupy precisely the same position during each successive operation. The position of the strips is further controlled by the links 22 and toggle means 23 permitting accurate placement and controlled application of initial pressures. The arrangement of the links 44 and 22, together with the toggle means 23 being such that "the side ;press1n'e member comprising the pressure strips I 8 initially urges the skin into engagement with the ribs adjacent the upper portion oi said member :and thereafter extends this engagement to areas positioned downwardly therefrom until the entire side of the work .is engaged.

Similarly, a nose pressure strip 24 .is pivetally mounted on the frame l] by links 25 land [tog 2.6 andadapted .to move upwardly and rearward-1y (or towards the side having the fixed strips 42 as shown in dotted .line) .to .clear the work area and to facilitate the assembly and removal .of the structural component. The effect .of successive operation .of the nose andmovableskin strips is to urge the skin as indicated ,by .the .arrows in Figure 4 and to draw it tight upon the ,ribs rather than merely clamping it in ,place. .Finally, the base pressure strips 21 corresponding to spar location are hinged to bracket 21 and their lateral .position is controlled by links 28 and toggles 2 9. Thes move laterally to clear the table area.

Each of the pressure strips is preferably of H section, as shown in Figure .3, and included in the inner face channel 13.0, are detent means .32 adapted to secure a rubber expansion tube 33 which extends along each of the pressure strips I8, 24 and 27.. Intake connections 34 are associated with the several expansion tubes 1'33, through which steam maybe admitted under the desired pressure to obtain the necessary heat and pressure for the settingof the adhesive .in the adjacent joints and exhaust connections 35 to remove steam and condensate from the tubes 33,. In some instances, these tubes may be continuously connected to form a skeleton-like structure in which all of the tubes are at the same tempera-- ture and pressure, However, one of the principal advantages .of the apparatus shown here is that the various runs of tubes may be kept separate and maintained under different conditions of temperature .and pressure by suitable variation of the steam supplied to obtain the particular conditions which are found best for each portion of the structure. This is important when differin adhesives are to be used between different types of materials.

Still referring to :Figure 1, the apparatus shown is particularly valuable in the formation of any structure having a closed edge,suchas-the leading edge of a wing. This results the factthat'the nose press is operated separately from the side presses. It is possible to apply force progressively to the skin commencing at the closed edge, continuing over the wing section and concluding at the base or spar making it conform closely to the underlying rib structur to obtain the precise tourvature desired .and yet to graduate this iorce so as to avoid any danger of distortion or -cracking. Ineiiect, a sort of graduated squeezing action is obtained. .At the same time. a complete bond is obtained throughout the structure, and there is no tendency for failure of adhesion encountered when conventional upper and lower presses alone are used.

In operation, successive sections of the nose component are operated on by the press I6 as the component slides intermittently along the table 1:6,. The control @of heat and pressure makes the gluing operation 'a matter of minutes rather than hours so that practically continuous fabrication of uniform sections is possible although the fix- :ture itself is but a fraction of the size of the component worked on. In Figure 2, on the other hand, the structure "is not uniform in section but 'wriaible so that an :over-all fixture must be used.

In this way alone "is it possible to compensate for thenecessary variation of the wing section. Thus,

F the wing fixture :includes the upper and lower surface wing presses generally referred to as 36 and 3! and the nose press 38. The surface presses comprise .a number iof individual m'essu're strips (as inFigure 1.). such asiornose ribs or v iorrruer-s 39, spars .40, wing ribs M, etc. These, as before, are preferably of .-H section and include (the tubes 43.. The presses 36 and 3-1 are mo ably secured to a support which isnot shown but which corresponds in structure and purpose 101" of Figure l. The moyable connectionlikewise includes toe- .gle or like means by which thepress positions can be changed to admit preassembly of the work, imposition of initial pressure, curing of adhesive under heat and pressure, and clearing of the pressa .for work removal. However, presses 36 .and 3] are preferably arranged with the nose pres 38 downwardly sand in this position, press .38 may be xfixed and proper pressure :sequence applied to the work by engaging the :oomponents of .36 and .3?! successively .from the bottom upwardly, that is, the portion .of press 35 and 3] immediately adjacent th nose press .38 is brought into contact first and then they remainder of the, press .isswung into engagement. In this instance, the various pressure tubes are shown somewhat more clearly and it is apparent how the pressure may be varied-tor instance, between these defi-nmg the wing rib M and that in conjunction with the spar All to fit precisely the work which must be done and the type of adhesive used.

It is believed that the operation of the apparatus isrclear, and its advantage is that it confines pressure and heat necessary to effect an adhesive bond only to those portions of the structure where they are required and where the structure itself is adapted to resist suchrforces without distortion or failure. It is .also believed apparent .how "the gluing operation .may be facilitated and strictly controlled by proper control of individual tern peratures in individual portions as may be required by the conditions pertaining. ,AS an ex,

amplainsome of the joints there may be several;

thicknesses of material to be adhesively joined, in which case a greater amount :of heat and pressure may be required. Again, the materials to be joined may differ, requiring cements of different curing properties, .Inothers, there may be generally similar joint conditions, yet the heat and pressure necessarily required in one might cause, failure or destruction at the secondbecause-of ierence in underl ing structure. This is completely avoided in the present device in which due:

allowance is made .for all of these various iaotors. The press itself serves :asan assembly fixture ier,

the various components, -as.-is particularlyshownin Figure l, and the build-up and preliminary;

work may be dnnein the fixture. which .in turn;

secures these components without additional effort before the final assembly and curing step. This is a clear distinction to other methods in which it is necessary to secure the components,

as by nails or other means prior to the gluing step, 5

and later remove or cover the fastening means so employed. It is equally applicable to step-by-step gluing of long components having an unvarying cross-section or over-all gluing of nonsymmetrical components. In the present instance, it is only necessary to assemble .the various components with the adhesive therebetween, clamp the device and apply the requisite steam pressure which, in turn, effects an even pressure throughout and supplies the heat necessary for the completionof the adhesive bond. It permits the graduated application of pressure which is most useful in fabricating'closed structures or those having substantial surface curvature. Its application to the newer cements which require curing tem- 2 peratures in excess of 200 F. and pressures on the order of 250 to 350 pounds to square inch will be readily appreciated.

Some changes may be made in the steps of the method disclosed or the structure described without departing from the spirit of the invention, and it is the intention to cover by the claims such changes as may be reasonably included in the scope thereof.

The invention claimed is:

1. In a gluing fixture for structural components of rib and skin construction, a longitudinally extending support, press means located intermediate of said support, said press means including side pressure members movable laterally of said support and a hinged vertical press member disposed above said support, a toggle device associated with said vertical pressure member and selectively operable to move said member substantially vertically with respect to said support, 4

operating means to move said side pressure members laterally of said support, said pressure members comprising a plurality of tubular pressure strips formed of resilient material, said pressure strips being disposed in predetermined relationship with ribs on said component to be assembled therein, and means to admit steam under pres:

sure selectively to said pressure strips.

2. The structure of claim 1, which is further characterized in that each of the said pressure members comprise a channel having opposed flanges and inwardly extending projections at the ends of said flanges, said tubularpressure strip being disposed between said flanges and retained bysaid projections, a portion of said tubular pressure strips extending outwardly of said flanges, and a steam connection through th web of said channel .to said tubular member to admit steam under pressure thereto.

3. In a gluing fixture for an aircraft wing component including the leading edge portion thereof and having as structural elements spaced ribs and a continuous skin conforming to said ribs, comprising, a longitudinally extending support, press means located above said support including a vertical pressure member and side pressure members intermediate said vertical pressure member and said support, said members adapted to operate upon the leading edge portion and the opposite skin surfaces of said component respectively, said vertical pressure member being hingedly mounted, one said side pressure member being fixed, the other side pressure member being hingedly mounted, said mounting of said lastnamed side pressure member comprising a link pivotally connected at one end to said member said links initially urging said skin into engagement with said ribs adjacent said vertical pressure member and thereafter occasioning such engagement at points successively more remote from said pressure member.

4. The structure of claim 3 which is further characterized in that vertical pressure member is pivotally supported at one end of a link member, the other member of said link being pivotally mounted on means fixed with respect to said support located adjacent to said fixed side pressure member, and means associated with last-named link to operate said vertical pressure member.

5. The structure of claim 1 which is further characterized in that there are lower pressure members beneath said side pressure members each having a pressure strip extending along said supportingmeans on opposite sides thereof, at leastv one of said lower pressure members being movable. independently of said side pressure members laterally of said supporting means.

CLARENCE F. KRAMER. WALTER. G. NELSON. 

